1. Field of the Invention
The present invention relates to a fixing device for fixing a toner image formed on a recording medium, and an image forming apparatus including the fixing device.
2. Description of the Related Art
In an electrophotographic image forming apparatus, a photoconductor drum is charged almost uniformly and is then exposed, for example, by a laser scanning unit to form an electrostatic latent image in accordance with an image signal. Thereafter, toner charged by a developing unit is supplied to the photoconductor drum to form a visual image. The resultant toner image is transferred to a recording medium such as transfer paper. Since the toner image transferred on the recording medium is only carried on the recording medium and has not yet been fixed, the toner image is heated and pressed by a fixing device included in the image forming apparatus, and thus thermally fused and fixed. Accordingly, an image fixed on the recording medium is formed. In such a fixing device, a toner image on a recording medium is fixed on a heating roller.
A variety of techniques have been disclosed for reducing energy consumption in a fixing device by reducing energy required to heat a heating roller.
For example, Document 1 (Japanese Laid-Open Patent Publication No. 05-188805), Document 2 (Japanese Laid-Open Patent Publication No. 09-101700), and Document 3 (Japanese Laid-Open Patent Publication No. 2007-086452) disclose a fixing device including a heating roller in a resin housing, in which a heat reflecting plate for bringing more heat from the heating roller back to the heating roller is provided between the resin housing and the heating roller.
Document 4 (Japanese Laid-Open Patent Publication No. 2004-287318) discloses a fixing device including, in addition to a heat reflecting plate as described above, a cleaner for cleaning a surface of a heating roller to prevent reduction of durability of the heating roller. According to those techniques, heat radiated from a heating roller is returned to the heating roller by a heat reflecting plate, so that energy required to heat the heating roller can be reduced.
However, as the conventional fixing device as disclosed in Documents 1 to 3 is used over time, toner or wax contained in toner and paper dust adhere to the surface of the heat reflecting plate to reduce heat reflecting efficiency. When a cleaner is provided in a fixing device as disclosed in Document 4, the complicated structure increases the cost of the fixing device.